I have an Asus F3 laptop and it appears the battery is dead after just over 2 years. I need to plug my machine in - in order for it to work. I am going to buy a new battery - however before I do that could it be something else that's wrong or does it sound glaringly obvious that it's the battery?

well, in my opinion, when u first got your new laptop and battery, the work time is different from the performace your battery play now. full charge the laptop battery and compare with the work time, if it is over half of the new one, you should change it. for most battery can be normal used in 400-500 charge and discharge circles.